I've often seen it said that in an Electromagnetic Wave the changing Electric Field component creates the Magnetic Field Component and the changing Magnetic Field Component in turn creates an Electric Field Component. This is then used as an explanation that Electromagnetic Waves are "self-sustaining" and do not require a medium.
Do modern Physicists really think about Electromagnetic Waves in this way? Is this kind of propagation "mechanism" really even needed?
The first thing I noticed is that the Electric and Magnetic Field Components oscillate in-phase which suggests (to me at least) that energy isn't being transferred in between them as they both reach their maximum simultaneously.
As well it seems as if the Magnetic Field would be much too weak at 1/c proportional to re-create an Electric Field ~300 million times stronger than it. (See comments.)
Finally if Electromagnetic Waves are simply changes in the Electromagnetic Field propagating through space is any kind of additional "mechanism" even really needed?
Best Answer
I expect there is variability among all the people who study Maxwell's equations. Here's my take. The equations and all the quantities they contain are mathematical abstractions. We use these abstractions in prescribed ways to come up with some predictions for field values, powers, etc. We map these predictions to observable, measurable phenomena like resistors heating up or needles flicking on a dial. How you get these predictions really doesn't depend on how you think about the details of propagation. The solutions to Maxwell's equations are, regardless of how you think about them. We then go out and do some experiments to see if our predictions matched our measurements. When we do this, we find that Maxwell's equations are good predictors of every observed classical EM phenomenon. In this context, questions about the nature of $E$ and $B$ "creating" each other become kind of meaningless. What we have is a theory that describes experiment when we use it. How we choose to interpret the details of the theory don't change it's predictions; the only benefits to thinking about it one particular way or another is to help us intuit, recall, explain, or reason about the theory. In those areas, I find the idea that "$E$ begets $B$ begets $E$ begets $B$ begets ..." can be useful for recalling the two curl equations and how they combine into wave equations, or for how the Yee grid FDTD method works. But if you ask me if this is what is "really" happening when I flip on the light switch, my answer is "I can predict many useful things about the light when the switch is flipped without knowing the answer to your question."